Method of briqueting flue-dust.



. dust may UNITED STATES PATENT OFFICE.

GEORGE L. COLLARD, 0F SHARON, PENNSYLVANIA.

METHOD OF BRIQUETING FLUE-DUST.

No Drawing.

To all whom, it may concern Be it known that I, GEORGE L. CoLLARD', acitizen of the United States, residing at Sharon, in the county ofMercer and State of Pennsylvania, have invented new and usefulImprovements in Methods of Briqueting Flue-Dust, of which the followingis a specification.

This invention relates to a method of briqueting flue dust, or the like,whereby the same may be readily and conveniently subjected to blastfurnaces or other metallurgical treatment.

In operation of blast furnaces, and particularly in the manufacture ofpig iron, considerable waste occurs when certain kinds of ores are usedby reason of a large percentage of the ore being carried out of thefurnace in the form of a fine dust, commonly referred to as flue dust.In order to prevent this flue dust from escaping from the furnace and toprotect the premises in the vicinity of the blast furnace, variousdevices have been utilized to trap the dust as it is about to leave thefurnace. The flue dust thus trapped is treated as a waste product as itis normally unfit to be again introduced into the furnace because of itsextreme lightness and the readiness with which it will blow out of thefurnace again on encountering the blast. It is well known, however, thatthis flue dust contains a sufliciently high percentage of metal torender it valuable and it is therefore desirable to so modify itscondition that it will be rendered capable of being treated in the blastfurnace in like manner as the heavier ores.

The object of the present invention is to provide means whereby the traped flue be afterward so trea that it will be held together in solidblocks or masses so that it may be fed into the blast furnaces in thesame manner as the ore, to the end that the metal contained in said fluedust may be extracted in the course of the furnace operation.

In carrying out my process, I mix the flue dust with crushed or powderedlimestone, and then add suflicient sulfuric acid and water to themixture, to form a plastic mass which may be molded into any desiredform and allowed to set. The plastic mass acts as a matrix to hold theflue dust, and on .being molded and allowed to set retains the flue dustin solid bodies, suitable for use in the Specification 01' LettersPatent. v Patented Dec. 17, 1912. Application filed September 8, 1911.Serial No. 648,268. A

blast furnace and possessing sufiicient weight to prevent its beingblown out before meltmg.

Lime, in any form, if mixed with flue dust in sufficient quantities, andif properly treated with sulfuric acid and water, will produce thedesired results, but I prefer to add crushed or powdered limestone tothe flue dust rather than add lime, for the reason that the limestone isthe cheaper of the two, and for the additional reason that when the acidcomes in contact with the limestone, gas is set free, which produces aviolent ebullition, that serves to intimately mix the plastic matterinto and throughout the flue dust, better, cheaper, and more thoroughlythan can be accom lished in other ways.

In practice, if tiie flue dust contains but little lime and not toexceed one half of one per cent. as is frequently the case, I usuallymix with the flue dust about three to four per cent. of crushed orpowdered limestone. Sufiicient water is then added to moisten the massand render it in the condition of mortar and suitable for molding intoany desired forms. It is then treated with the sulfuric acid and stirredor mixed until the mass ceases to emit gas bubbles, or the water and theacid may be added together.

If the flue dust is rich in its lime content, a less amount of thecrushed or powdered limestone may be added and fairly good results maybe thus obtained, but in an event I prefer to add some of the crusliedor powdered limestone in order to obtain the good results which areproduced by the ebullition of the gas that is discharged when the acidcomes in contact with and attacks the limestone.

Experiment has demonstrated that when briquets made according to myprocess are introduced into the furnace, the flue dust is maintained ina coherent mass until the temperature of the briquet is raised sufliciently high to melt the metal contained therein.

From what has been said it will be noted that I utilize the lime alreadypresent in the flue dust and thereby obtain the best results with theleast admixture of foreign ingredients with the material to be treated.

In place of the-limestone dolomite may be used and fairly good resultsmay be obtained.

In practising the invention, the plastic 0 mass may be molded by hand,or any of the ordinary forms of briqueting apparatus may be used.

Vhile my inventionis especially applicable in connection with blastfurnace practice for saving the flue dust, I donot desire to limitmyself thereto as it maybe employed in all cases when it is desirable tobriquet finely communited ore.

I claimas my invention 1. The process of briqueting finely comminutedore or flue dust comprising adding limestone, sulfuric acid, and Waterto such ore to form a plastic mass and then forming the mass into thedesired shape, While in a plastic condition.

2. The process of briqueting' finely comminuted ore or flue dustcomprising the mixing of crushed limestone with the ore, then addingsulfuric acid and water to the mixture, and finally molding the mass.

3. The process of briqueting finely comminuted ore or flue dust.containing lime, comprising the mixing of crushed limestone with the oreandthen adding approximately harden.

5. The process of briqueting finely comminuted ore or flue dustcomprising the mixing of crushed limestone With the ore, then addingsulfuric acid to the mixture and stirring the latter until ebullitionceases, and

finally molding the mass.

In testimony whereof I have hereunto set my hand in presence of twosubscrlbmg wit-- nesses.

GEORGE L. COLLARD.

\Vit-nesses:

CHARLES H. MoKEE, F. E. GAITHER.

